filius est pars patris
by seilleanmor
Summary: A prequel of sorts to my fic 'fugaces labuntur anni', although you don't need to have read that to understand this. The life of Alexander James Castle.
1. Chapter 1

**filius est pars patris**

_a son is part of the father_

* * *

_Because I haven't been able to stop thinking about a little boy with blue eyes and a cheeky grin who pulls his mommy back from the rabbit hole every day. You don't have to have read _fugaces labuntur anni _to understand, in fact this is a prequel. All you need to know is that Castle died in Dreamworld, and Kate was pregnant from their night in the bathroom. _

* * *

When Martha startles awake, it's to a sucking sense of urgency and the desperate touch of Katherine's fingers at her shoulder. Even in the velvety darkness of – oh man – three in the morning, her daughter in law's eyes are wide and beseeching and so rich with life. They've talked about it some, she and Katherine. The younger woman hopes that the baby has his father's eyes, but Martha knows how much her son would have wanted the opposite.

After all, Katherine's eyes were the very first thing about her that grabbed a hold of him. The thing that he couldn't stop talking about for days after he first met the beautiful, willowy detective who didn't cut him any sort of slack. There's a sheen of sweat at Katherine's forehead and then she grits her teeth and drops a hand to the mattress to keep herself standing, the ripple of tension across her stomach visible even underneath her shirt.

"Martha." She says quietly, after a minute or so where she seems to climb inside of herself, all of the shutters slamming down. "Baby's coming."

Oh God. Okay.

Richard is gone. Richard is never going to meet his baby. Richard is not here to help his fiancée through the birth of their child, so Martha will be here instead. "Alright darling. Has your water broken?"

"No. But the contractions are maybe five minutes apart." Katherine says, sucking in a breath through her teeth.

Martha shoves the sheets away from her legs and climbs out of bed, settling a palm at Katherine's spine, low down where her hips flare. With her free hand, she peels her quasi-daughter's hand off of the mattress and takes as much of the younger woman's weight as she can, dropping a kiss to the top of Katherine's head. "We have to get to the hospital, honey. Why didn't you wake me sooner?"

"I figured one of us should get as much sleep as possible." She grunts, straightening up slowly and releasing a long breath. "I called Lanie and my dad to meet us there."

Cupping Katherine's elbows in her palms, Martha guides the detective to sit on the bed and tucks the wild spill of her curls back behind her ear. "Let me just get dressed. Are you alright to go like that or did you want to change?"

"I'm good like this." Katherine manages a smile, rubbing one hand over her stomach. Swollen with her child, and Martha has never seen her look so radiant as these past few months. Even if grief does hover at the edges of everything they do, just waiting to sink its claws in and drag them both down to drowning.

"Alright. You need anything?"

There's a moment where Katherine goes completely still, even the constant motion of her hand smoothing over her child ceases. And then she lifts her head and the liquid heat that floods her eyes spills right over and down her cheeks, her mouth open on a sob that never makes it out.

"I need him. Martha. Oh God. How do I do this without him?"

Abandoning all notions of giving Katherine space, Martha moves to sit at her side and wraps a slender arm around her shoulders, so very grateful when Katherine sinks into her side and rests her head in the curve where Martha's neck meets her shoulder.

"It will be hard. But you're so strong, Katherine. And you're not alone. I'm here, and Jim and Dr Parish will be right there with you too. And Alexis." Martha murmurs against the shell of the younger woman's ear. The very worst part about all of this is that Martha can picture so clearly just how excited her son would be. Absolutely overjoyed, and enraptured with his fiancée and with the baby.

They both know it, and the spectre of Richard's absence looms heavily. Martha stands slowly and squeezes Katherine's shoulder, stepping inside of the closet to dress as hurriedly as she can. From outside, the slow hiss of air through Katherine's teeth is the only hallmark of another contraction, but all the same it spurs Martha on.

She only hopes the baby will be a balm to help heal the ragged edges of their grief.

* * *

Her son.

Her _son_, and he's the most perfect thing she's ever seen.

Only five hours old. She can't believe he's here, can't manage to take her eyes off of him. Martha and Alexis and Lanie and her father all took a turn to hold him and then the boys and Jenny crowded into the hospital room as well. Everyone fawning over Kate's son, yes, but she's not stupid. She knows a lot of it was about showing her she's not alone. That her son is loved, and that Kate herself is too. Now though, they're all home sleeping and Kate gets to have her beautiful baby boy all to herself.

Bittersweet, the fact that she doesn't have to share. If Rick were here, he'd be clamouring for a turn with their son. Letting her eyes slip closed, Kate imagines how the baby would be dwarfed against Castle's broad chest, the look on his face when he stared down at this amazing little person they've made together.

The baby stirs, rooting at her chest and a little fist escapes from the blanket, opening out so tiny fingers splay at the bare skin above the neckline of Kate's shirt. Stroking a finger over the curve of her son's cheek, Kate bites her lip to battle back the choke of raw emotion. It's so hard to distinguish between the love that pours over her in waves, the lightning bolt that Castle told her about, and the suffocating grief of not having him here for this.

"Hi, my sweet boy. Mommy's here." The baby's eyelids open, the thin skin peeling back to reveal eyes as startling blue as his father's. Kate leans down and dusts her mouth to his forehead, his cheek, the smell of him already so familiar.

His eyes settle on her face and she laughs softly, tears spilling over again. She doesn't care anymore. It doesn't matter. Her little boy is here, her son, and her tears are half in delight. "Oh, hi beautiful boy. Hello. I love you."

Her words are only for her son, murmured against the tiny, perfect shell of his ear, and Kate cradles his skull in her palm. So much hair, all of the nurses have commented on it. Her father said that Kate's son is like his mother in that respect, dark hair sticking up all over the place when he was born just like Kate.

"Alexander James, you are so loved." She hums for him, grinning when his eyes startle open at the sound of his mother's voice. "You heard me, huh baby? Yeah? Hi. I'm your mommy."

Oh god, her son. She can't actually believe that he's here, that together she and Castle made this perfect little person with thoughts and ideas and a whole life spanning ahead of him. A life without his father, and that guts her, but she's so in love with her baby boy that for the first time since she lost Rick, his absence is not at the forefront of her mind.

Instead, the tiny fingers and toes and perfect rosebud mouth and long, fragile lashes of her son. "I wish your daddy was here, sweet boy. He would love you so much."

Alexander roots at Kate's chest again, a mewling cry clueing her in to what he needs. Kate lifts her shirt and unfastens the nursing bra, guides the baby to latch on at her breast. He didn't have any trouble figuring out what he's supposed to do here and he sucks greedily, his fingers opening and closing into a fist over and over again where his hand rests at her chest.

"There you go, little man. You're pretty hungry, huh?" She murmurs, and her voice startles him so he stops feeding and his head tips back to look at her. "I'm sorry, baby." She laughs, smoothing her thumb in gentle circles at his crown over and over again until he refocuses his attention at her breast.

Her body aches all over, and more than anything she wishes Castle were here. Falling all over himself trying to get her whatever she needs, when really all she needs is the warmth of him next to her and the touch of his mouth.

It's not that she's worried she can't do it alone; Martha and Alexis and Jim have all volunteered to help her as much as she needs. It's just that Rick is – was – such a wonderful father to Alexis. And she can't help but feel as if she's cheated her son out of it.

The little boy who Alexis named and who is named for Jim too. Her son, so loved by so many people. Right there, in the hospital bed with her brand new little boy in her arms, Kate vows to herself and to him that she'll try to get this right. Be the best mom she can be, and try to do for her son what Castle would have. Make everything an adventure.

She's better at it, now. Fun, laughter, enveloping the joy in her life and grabbing onto it with both hands. Even though Rick's loss is crushing, she's better for having loved him.

"Alexander." Kate hums against her son's cheek, dusting a kiss there and then pulling back just enough to look at him. "Daddy loves you so much. So, so much, baby. And Mommy too, and Gram and Papa and your sister and your aunts and uncles."

Already, her son's eyes are slipping closed. There's a bassinet right next to the bed and the nurses told her to put Alexander down when he was sleeping, to try and get some sleep herself. She just. . .can't make herself let go of him. This perfect, beautiful little boy who she loves so much. Even though it hurts, to see so much of Castle in him, it's good too. So good to still have a piece of the man she loves with her.

Kate shifts the pillows and lies down in the hospital bed, her son's weight comforting and familiar on her chest, and she sleeps.

* * *

_There will probably be more of this. _

**Tumblr:** katiehoughton

**Twitter:** seilleanmor


	2. Chapter 2

**filius est pars patris**

* * *

"Mommy?" Her son's tentative voice comes quiet into the stillness of the early morning, the hot wash of his breath against her cheek and his body so warm and wriggly in the bed next to her.

Immediately awake, Kate rolls over and splays her palm at Alexander's spine, drags him in close so she can get both arms around him. "Hey sweet boy. You okay?"

Stifling a yawn, she buries her nose in the thickness of her little boy's curls and breathes in the scent of him, apple shampoo and sunshine and a little sleep-sweat too. She can't remember the last time she got a truly good night's sleep.

The thing is. . .it's only her. Sure, Martha's here, but even if Alexander's grandmother does get up with him, she only has to wake Kate anyway. The boy is only ever soothed by his mother's embrace. So Beckett sleeps shallowly, always half-listening for the cries of her child.

"I'm a bit sad." Her son is saying into the crease of her neck, and when she peels back to look at him his face is drawn, his bottom lip protruding.

Brushing her thumb over it, Kate scatters kisses across his cheeks until she gets the spill of giggles from him and he squirms, presses tiny hands to his cheeks. The headboard is padded, comfortable against her back when she leans against it and cradles her son in her lap, rocking him like a newborn until he starfishes and flops around in mirth.

"Why are you sad, baby?"

He stills at that, pushes his hair back off of his forehead with both hands and reaches up to curl his fingers in the neckline of her sleep shirt. "It's daddy's day. And I don't have one."

Curling an arm underneath her son, Kate scoops him up and clutches him tight to her chest. This week has been tough on him, she knows. At preschool they've been making father's day cards and casting their handprints in clay and writing poems entitled _My Daddy and Me_. All exactly the sort of thing Rick would have adored, showed off to anyone who would listen. She can almost hear him now, voice thick with pride. _My son made this for me_.

Obviously, AJ's preschool teacher is conscious of the situation. He was allowed to double up on everything, make two cards and two sets of handprints and write two poems. One for Tío and one for Uncle Kevin. Kate is so unspeakably grateful for how her boys at the precinct have stepped up, each of them acting as a surrogate father for Kate's son.

It's not the same, but just having someone who can rough around in the park with him or take him to see the latest space ninja movie has been a blessing. Even so, it's hard on her little boy. There have been tears and tantrums when his classmates have gone on adventures with their fathers.

More than once, he's told her he wishes he had a daddy instead of her. It stings, of course it does, but she knows he doesn't really mean it. That it's just the hurt talking.

"Do you remember our plan for today?"

"Uh-huh." He whimpers, scrubbing his face against her shirt and Kate cups his shoulders, holding him away from her body a moment so she can press a kiss to the end of his nose. She won't let him get maudlin. They've talked about it, about how today is different for them than most families but that it can still be good.

Rick is not a spectre, not a ghost. He's a presence in their lives. Kate tells stories of him to their son like fairy tales, Alexander falling asleep in her arms to the quiet wash of words as she describes his daddy's strength, his heart and passion and the fun he infused her life with. She won't let Castle's memory be forgotten.

"We'll go see Daddy's grave and lay some flowers. You can tell him all those stories you wrote down." AJ keeps a list tacked to the refrigerator of all the things he wants to tell his father the next time they visit Castle's grave.

The two of them sit in front of the headstone together, Alexander alternately curled in her lap or steadfast and cross-legged at her side, and he spins a tale the way his daddy used to.

"What after that, Mommy?"

Kate cards a hand through her son's hair, kisses his cheek again. "We're going to see Papa for lunch, remember?"

"I can get a milkshake?" AJ perks up considerably at that prospect, grinning wide and giggling into the cup of his palms when he gets a nod of affirmation from his mother.

Slipping down in the sheets, Kate lets her son arrange himself to get comfortable. He ends up sprawled over her stomach and Kate smoothes her palm up and down his back, relishing the warm weight of him. "And this afternoon your sister has a surprise for you."

Alexis wants to take her brother to the aquarium. Sometimes, although it shames her to admit it, Kate forgets that Alexander is not the only one without a father. So even though it hurts to be apart from him, she knows that Alexis needs it too.

AJ is so very much like Rick that being around him is almost like having Castle back. So she can let Alexis have all the time with him she needs. It'll be good, too, to have time with Martha this afternoon.

Ostensibly to plan for AJ's birthday next month but also yes, because Castle's mother lost her son that day and Kate cannot imagine the depth of that grief. If she were to lose Alexander. . .

Unthinkable. So she does her best to be a daughter for Martha. Rick's mother is wonderful with AJ, too, often has to take care of him in the afternoons and at weekends if Kate can't get away from the precinct. A part of her had considered quitting, the risk of making her son an orphan too large to seem worth it.

It was Martha who persuaded her that she needed her precinct family, needed her job and that Castle would never have wanted her to stop being a detective.

"Mommy, are you sad too?" Her son asks, propping his chin in his hand. His elbow digs into her ribcage and she grunts, knocks him to sprawl on the mattress and blows a raspberry in the crease of his neck.

Kate rests her head at her son's chest, listens to the thunder of his heart and stifles a grin when he brings his hands up to pet her in much the same way she does to him. "Yes. It's okay to be a little bit sad, sweet boy. It's okay to miss Daddy."

"Can we have breakfast now?"

"Yeah." Kate laughs, sitting up and hooking her hands underneath her son's arms to swing him out of bed and to the floor. "Go ahead, I'm right behind you."

Alexander charges for the doorway and the living space beyond, socked feet skidding on the hardwood. Taking a moment in front of the mirror, Kate slips her engagement ring off of the chain she usually wears it on and settles it on her finger instead.

The weight of it always takes a moment to get used to, throws her off at first. But it's good. Raking her hands through her hair, Kate meets the eyes of the woman in the mirror and nods, stepping into her slippers and heading for the kitchen and the noises of her son.

* * *

Alexander has had a wonderful day.

Even though he's been a little bit sad, he's still had a good time with the people he loves most. Gram and Papa and Alexis and Mommy. Oh, his Mommy, who makes him feel okay being sad. Who tells him all about Daddy and how proud he would be.

Mommy's cuddles are the best in the whole world, and now he gets to be curled up inside the blanket with her while they watch a movie. Alexis and Gram are here too. They came for dinner and now they're still here and Mommy said that Alexis will stay until he falls asleep.

Today, he got to go talk to Daddy. AJ told him all about the pet dragon that his preschool class is taking care of, and how he went to the zoo with Mommy and saw a big big snake and she said maybe when he's a big boy he could get a pet snake or a dragon or something super cool.

When he was done telling Daddy all of his stories, he and Mommy went for lunch with Papa. He got to have milkshake – oh, so cold – and Mommy even let him dip his French fries into it. He ate up all his burger and he didn't even make a mess on his cool new Batman shirt with the tomato sauce.

Then later, at the aquarium, AJ and Alexis got to watch the sharks get fed. It was so so cool, to see their so-big mouths open up all wide and Alexis tickled his sides and said _better be careful, AJ, he could eat you all up_. And he wasn't even scared at all. Daddy would be proud of him.

Now he's really tired, though. He wants to stay awake to watch the movie because he's nearly _five_ and he's a big boy, but his eyes are heavy and Mommy is warm and smells good. And he knows it's okay to close his eyes now. Mommy keeps him safe, shows him how to make the sad go away.

He loves Daddy, and he would like it if he could have Daddy to play games with and tell him stories, but Mommy is the best.

"Alexander." She says, her voice all soft and nice. Her arms are so tight around him and he blinks his eyes open, looks up at her. "I love you, baby."

"I love you too, Mommy." He yawns.

Mommy stands up from the couch with him in her arms, carries him over first to Gram (her kiss is powdery and smells funny like her makeup) and then to Alexis who smells like vanilla and always kisses the same place on his forehead.

Then he feels the strange bumpiness of Mommy going up the stairs, his eyes screwed tight and his body all funny and heavy. He knows when they get to his room because it goes a bit darker behind his eyelids and then he feels his mattress underneath him, Mommy dragging the sheets up and tucking him in.

She always makes sure he has his teddy close by, and then she strokes his cheek and leans in to kiss him again. "I love you so much, baby. Even when I'm sad and I miss Daddy, you still make me so happy."

He's asleep before he hears Mommy leave.


End file.
